The following disclosure relates to a liquid ejection apparatus.
A conventional liquid ejection apparatus includes a multiplicity of piezoelectric elements configured to apply ejection pressure to liquid and arranged in rows. Each of the piezoelectric elements includes a piezoelectric layer interposed between an individual electrode as a driving electrode and a common electrode as a ground electrode. When a voltage is applied to the electrodes, the piezoelectric element is driven to apply the ejection pressure to the liquid. The common electrode is elongated in an arrangement direction, in which the piezoelectric elements are arranged, so as to cover these piezoelectric elements. The common electrode is connected to an external wire or board such as a Chip-on-Film (COF) via terminals provided on opposite end portions of the common electrode. In such a configuration, however, a piezoelectric element located near a center of the row in the arrangement direction is farther from the terminal for connection to the external wire or board than a piezoelectric element located near an end portion of the row in the arrangement direction. A voltage applied to the piezoelectric element decreases with increase in distance from the connection terminal, resulting in smaller amount of deformation of the piezoelectric element.
There is known a configuration for uniform voltages applied to piezoelectric elements. Specifically, there is known a liquid ejection head including individual electrodes and a common electrode, and this liquid ejection head is configured such that substantial driven portions (piezoelectric active portions) of respective piezoelectric elements defined by these electrodes are provided at regions respectively opposed to pressure generation chambers. The common electrode and a wire electrode provided along a direction in which the piezoelectric active portions are arranged are connected to each other by a common lead electrode provided between the piezoelectric active portions. This configuration ensures more uniform voltages applied to the respective piezoelectric elements.